Molecules 2011, 16, 8694-8732; doi:10.3390/molecules16108694 OPEN ACCESS molecules ISSN 1420-3049 www.mdpi.com/journal/molecules Review Alkaloids from Marine Ascidians Marialuisa Menna *, Ernesto Fattorusso and Concetta Imperatore The NeaNat Group, Dipartimento di Chimica delle Sostanze Naturali, Università degli Studi di Napoli “Federico II”, Via D. Montesano 49, 80131, Napoli, Italy * Author to whom correspondence should be addressed; E-Mail:
[email protected]; Tel.: +39-081-678-518; Fax: +39-081-678-552. Received: 16 September 2011; in revised form: 11 October 2011 / Accepted: 14 October 2011 / Published: 19 October 2011 Abstract: About 300 alkaloid structures isolated from marine ascidians are discussed in term of their occurrence, structural type and reported pharmacological activity. Some major groups (e.g., the lamellarins and the ecteinascidins) are discussed in detail, highlighting their potential as therapeutic agents for the treatment of cancer or viral infections. Keywords: natural products; alkaloids; ascidians; ecteinascidis; lamellarins 1. Introduction Ascidians belong to the phylum Chordata, which encompasses all vertebrate animals, including mammals and, therefore, they represent the most highly evolved group of animals commonly investigated by marine natural products chemists. Together with the other classes (Thaliacea, Appendicularia, and Sorberacea) included in the subphylum Urochordata (=Tunicata), members of the class Ascidiacea are commonly referred to as tunicates, because their body is covered by a saclike case or tunic, or as sea squirts, because many species expel streams of water through a siphon when disturbed. There are roughly 3,000 living species of tunicates, of which ascidians are the most abundant and, thus, the mostly chemically investigated.